Balance of Probabilities in UK Law

It is accepted that the risk of developing a mesothelioma increases in proportion to the quantity of asbestos dust and fibres inhaled: the greater the quantity of dust and fibre inhaled, the greater the risk. But the condition may be caused by a single fibre, or a few fibres, or many fibres: medical opinion holds none of these possibilities to be more probable than any other, and the condition once caused is not aggravated by further exposure.

It would need more cogent evidence to satisfy one that the creature seen walking in Regent's Park was more likely than not to have been a lioness than to be satisfied to the same standard of probability that it was an Alsatian. In this basis, cogent evidence is generally required to satisfy a civil tribunal that a person has been fraudulent or behaved in some other reprehensible manner. But the question is always whether the tribunal thinks it more probable than not.

Anything that is more probable than not it treats as certain. But in assessing damages which depend upon its view as to what will happen in the future or would have happened in the future if something had not happened in the past, the court must make an estimate as to what are the chances that a particular thing will or would have happened and reflect those chances, whether they are more of less than even; in the amount of damages which it awards.

The bare facts of a difference in status and a difference in treatment only indicate a possibility of discrimination. They are not, without more, sufficient material from which a tribunal “could conclude” that, on the balance of probabilities, the respondent had committed an unlawful act of discrimination.

However, I agree that, given the seriousness of matters involved, at least some reference to the heightened civil standard would usually be necessary: In re H (Minors)(Sexual Abuse: Standard of Proof) [1996] AC 563, 586D-H, per Lord Nicholls of Birkenhead. But in my view pragmatism dictates that the task of magistrates should be made more straightforward by ruling that they must in all cases under section 1 apply the criminal standard.

Parliament might, of course, have taken what was conceded in argument to be a fair and sensible course. It could have said, in appropriate words, that a person is to be liable unless he proves that he had no knowledge or guilty mind. But it would be very much harder for the guilty to escape if the burden of disproving mens rea or knowledge is thrown on the defendant.

Particularly is this so if the words which are used to define that approach are the servants but not the masters of meaning. Though no Court and no jury would give less careful attention to issues lacking gravity than to those marked by it, the very elements of gravity become a part of the whole range of circumstances which have to be weighed in the scale when deciding as to the balance of probabilities.